1. Field of the Invention
The invention relates to an improved pump and process for pumping latexes or latex drag reducing agents, also referred to as drag reducing additives or flow improvers. More particularly, the invention relates to diaphragm pumps, a method to transport a latex drag reducer, and a method to reduce the pressure drop associated with flowing a hydrocarbon-containing fluid through a pipeline.
2. Description of the Prior Art
When fluids are transported by a pipeline, a drop in fluid pressure typically occurs due to friction between the wall of the pipeline and the fluid. Due to this pressure drop, for a given pipeline, fluid must be transported with sufficient pressure to achieve a desired throughput. When higher flow rates are desired through the pipeline, more pressure must be applied due to the fact that as flow rates are increased the difference in pressure caused by the pressure drop also increases. However, design limitations on pipelines limit the amount of pressure that can be employed. The problems associated with pressure drop are most acute when fluids are transported over long distances. Such pressure drops can result in inefficiencies that increase equipment and operation costs.
To alleviate the problems associated with pressure drop, many in the industry utilize drag reducing additives in the flowing fluid. When the flow of fluid in a pipeline is turbulent, high molecular weight polymeric drag reducers can be employed to enhance the flow. A drag reducer is a composition capable of substantially reducing friction loss associated with the turbulent flow of fluid through a pipeline. The role of these additives is to suppress the growth of turbulent eddies, which results in higher flow rate at a constant pumping pressure. Ultra-high molecular weight polymers are known to function well as drag reducers, particularly in hydrocarbon liquids. In general, drag reduction depends in part upon the molecular weight of the polymer additive and its ability to dissolve in the hydrocarbon under turbulent flow. It has been found that effective drag reduction can be achieved by employing drag reducing polymers having number average molecular weights in excess of five million. However, despite these advances in the field of drag reducing polymers, a need still exists for improved drag reducers.
As improved drag reducers are developed, the pumps available to pump the drag reducers into pipelines cannot always effectively pump drag reducers and maintain pump pressure. The pumps can become plugged with drag reducer or other components and valuable time is spent to open, clean and maintain the pumps. There is a need for reliable pumps to maintain a steady and/or constant flow of drag reducers into a pipeline.